Generally, the “cloud” refers to computing resources, such as software, services, and information, connected via a network, e.g., the Internet. “Cloud computing” can thus be defined as Internet-based computing in which these computing resources are dynamically provisioned and allocated to client or user computers or other devices on-demand from a pool of resources available via the cloud. Cloud computing is envisioned as a way to allocate access to these resources according to particular needs of a user.
Allocating access to resources in a cloud computing environment presents various challenges. For example, there is an ever increasing number of computing resources within the cloud possessing an ever increasing variety of capabilities and attributes, and, further, there are an ever increasing number of users having various computing needs. Selecting particular resources for a given task is thus a complex problem. These challenges are particularly enhanced for distributed computing jobs having multiple phases, where the resources needed for subsequent phases of processing are typically unknown at the start of the job.